Can you tell a real Warhol from a fake? Four art exhibitions to see for free

A show of smart forgeries by Sturtevant will test your critical eye. Elsewhere, there’s a chance to dissect America’s cultural corpse and enter a terrifying immersive painting of Mexico

Cady Noland’s US is a violent, celebrity obsessed, consumerist police state. In this small show of big, stark, awkwardly cropped and blurry black and white images and minimal sculptures, the influential American iconoclast is dissecting her country’s cultural detritus, and leaving its splayed corpse on display.